Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Electrochemical amperometric sensors measure concentrations of an analyte by measuring currents generated through electrochemical oxidation or reduction reactions of the analyte at the working electrodes of the sensors. A reduction reaction occurs when the electrons are transferred from the electrode to the analyte, whereas an oxidation reaction occurs when the electrons are transferred from the analyte to the electrode. The direction of the electron transfer is dependent upon electrical potentials applied to the working electrode. At least one other electrode (e.g., a counter electrode, a reference electrode) can complete the circuit. When the working electrode is appropriately biased, the output current can be proportional to the reaction rate, which can provide a measure of the concentration of the analyte surrounding the working electrode. Depending on the diffusion characteristics of the analyte in the environment surrounding the working electrode, the reaction rate (and associated current) may be diffusion limited because the analyte can be reduced or oxidized faster than it is replenished at the working electrode via diffusion.